diff --git a/README.md b/README.md
index c0c8fff..a821183 100644
--- a/README.md
+++ b/README.md
@@ -224,12 +224,12 @@ moment there is nothing setup to do so. If this is something you need feel free
 
 Name | Default | Notes
 |--|--|--|
-LOG_LEVEL | info | Used to change the verbosity of the logging. Use `LOG_LEVEL=debug` for more information.
-LOG_HTML | false | Used for debugging. If `true` all HTML that passes through the proxy will be logged to the console in `debug` level.
-PORT | 8191 | Change this if you already have a process running on port `8191`.
-HOST | 0.0.0.0 | This shouldn't need to be messed with but if you insist, it's here!
-CAPTCHA_SOLVER | none | This is used to select which captcha solving method it used when a captcha is encountered.
-HEADLESS | true | This is used to debug the browser by not running it in headless mode.
+LOG_LEVEL | info | Verbosity of the logging. Use `LOG_LEVEL=debug` for more information.
+LOG_HTML | false | Only for debugging. If `true` all HTML that passes through the proxy will be logged to the console in `debug` level.
+CAPTCHA_SOLVER | none | Captcha solving method. It used when a captcha is encountered. See the Captcha Solvers section.
+HEADLESS | true | Only for debugging. To run the web browser in headless mode or visible.
+PORT | 8191 | Listening port. You don't need to change this if you are running on Docker.
+HOST | 0.0.0.0 | Listening interface. You don't need to change this if you are running on Docker.
 
 Environment variables are set differently depending on the operating system. Some examples:
 * Docker: Take a look at the Docker section in this document. Environment variables can be set in the `docker-compose.yml` file or in the Docker CLI command.
diff --git a/src/captcha/index.ts b/src/captcha/index.ts
index 0f950b0..de045dd 100644
--- a/src/captcha/index.ts
+++ b/src/captcha/index.ts
@@ -30,12 +30,12 @@ export default (): Solver => {
         throw Error(`The solver '${method}' is not a valid captcha solving method.`)
       } else {
         console.error(e)
-        throw Error(`An error occured loading the solver '${method}'.`)
+        throw Error(`An error occurred loading the solver '${method}'.`)
       }
     }
   }
 
-  log.info(`Using '${method} to solve the captcha.`);
+  log.info(`Using '${method}' to solve the captcha.`);
 
   return captchaSolvers[method]
 }
diff --git a/src/index.ts b/src/index.ts
index 6f90ed3..4d1ef7d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,11 +2,33 @@ import log from './log'
 import { createServer, IncomingMessage, ServerResponse } from 'http';
 import { RequestContext } from './types'
 import Router, { BaseAPICall } from './routes'
+import getCaptchaSolver from "./captcha";
 
 const version: string = "v" + require('../package.json').version
 const serverPort: number = Number(process.env.PORT) || 8191
 const serverHost: string = process.env.HOST || '0.0.0.0'
 
+function validateEnvironmentVariables() {
+  // ip and port variables are validated by nodejs
+  if (process.env.LOG_LEVEL && ['error', 'warn', 'info', 'verbose', 'debug'].indexOf(process.env.LOG_LEVEL) == -1) {
+    log.error(`The environment variable 'LOG_LEVEL' is wrong. Check the documentation.`);
+    process.exit(1);
+  }
+  if (process.env.LOG_HTML && ['true', 'false'].indexOf(process.env.LOG_HTML) == -1) {
+    log.error(`The environment variable 'LOG_HTML' is wrong. Check the documentation.`);
+    process.exit(1);
+  }
+  if (process.env.HEADLESS && ['true', 'false'].indexOf(process.env.HEADLESS) == -1) {
+    log.error(`The environment variable 'HEADLESS' is wrong. Check the documentation.`);
+    process.exit(1);
+  }
+  try {
+    getCaptchaSolver();
+  } catch (e) {
+    log.error(`The environment variable 'CAPTCHA_SOLVER' is wrong. ${e.message}`);
+    process.exit(1);
+  }
+}
 
 function errorResponse(errorMsg: string, res: ServerResponse, startTimestamp: number) {
   log.error(errorMsg)
@@ -64,6 +86,9 @@ function validateIncomingRequest(ctx: RequestContext, params: BaseAPICall) {
   return true
 }
 
+// init
+validateEnvironmentVariables();
+
 createServer((req: IncomingMessage, res: ServerResponse) => {
   const startTimestamp = Date.now()